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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __ASMARM_TLS_H
#define __ASMARM_TLS_H
#include <linux/compiler.h>
#include <asm/thread_info.h>
#ifdef __ASSEMBLY__
#include <asm/asm-offsets.h>
.macro switch_tls_none, base, tp, tpuser, tmp1, tmp2
.endm
.macro switch_tls_v6k, base, tp, tpuser, tmp1, tmp2
mrc p15, 0, \tmp2, c13, c0, 2 @ get the user r/w register
#ifndef CONFIG_CURRENT_POINTER_IN_TPIDRURO
mcr p15, 0, \tp, c13, c0, 3 @ set TLS register
#endif
mcr p15, 0, \tpuser, c13, c0, 2 @ and the user r/w register
str \tmp2, [\base, #TI_TP_VALUE + 4] @ save it
.endm
.macro switch_tls_v6, base, tp, tpuser, tmp1, tmp2
ldr \tmp1, =elf_hwcap
ldr \tmp1, [\tmp1, #0]
mov \tmp2, #0xffff0fff
tst \tmp1, #HWCAP_TLS @ hardware TLS available?
streq \tp, [\tmp2, #-15] @ set TLS value at 0xffff0ff0
mrcne p15, 0, \tmp2, c13, c0, 2 @ get the user r/w register
mcrne p15, 0, \tp, c13, c0, 3 @ yes, set TLS register
mcrne p15, 0, \tpuser, c13, c0, 2 @ set user r/w register
strne \tmp2, [\base, #TI_TP_VALUE + 4] @ save it
.endm
.macro switch_tls_software, base, tp, tpuser, tmp1, tmp2
mov \tmp1, #0xffff0fff
str \tp, [\tmp1, #-15] @ set TLS value at 0xffff0ff0
.endm
#endif
#ifdef CONFIG_TLS_REG_EMUL
#define tls_emu 1
#define has_tls_reg 1
#define switch_tls switch_tls_none
#elif defined(CONFIG_CPU_V6)
#define tls_emu 0
#define has_tls_reg (elf_hwcap & HWCAP_TLS)
#define switch_tls switch_tls_v6
#elif defined(CONFIG_CPU_32v6K)
#define tls_emu 0
#define has_tls_reg 1
#define switch_tls switch_tls_v6k
#else
#define tls_emu 0
#define has_tls_reg 0
#define switch_tls switch_tls_software
#endif
#ifndef __ASSEMBLY__
static inline void set_tls(unsigned long val)
{
struct thread_info *thread;
thread = current_thread_info();
thread->tp_value[0] = val;
/*
* This code runs with preemption enabled and therefore must
* be reentrant with respect to switch_tls.
*
* We need to ensure ordering between the shadow state and the
* hardware state, so that we don't corrupt the hardware state
* with a stale shadow state during context switch.
*
* If we're preempted here, switch_tls will load TPIDRURO from
* thread_info upon resuming execution and the following mcr
* is merely redundant.
*/
barrier();
if (!tls_emu && !IS_ENABLED(CONFIG_CURRENT_POINTER_IN_TPIDRURO)) {
if (has_tls_reg) {
asm("mcr p15, 0, %0, c13, c0, 3"
: : "r" (val));
} else {
#ifdef CONFIG_KUSER_HELPERS
/*
* User space must never try to access this
* directly. Expect your app to break
* eventually if you do so. The user helper
* at 0xffff0fe0 must be used instead. (see
* entry-armv.S for details)
*/
*((unsigned int *)0xffff0ff0) = val;
#endif
}
}
}
static inline unsigned long get_tpuser(void)
{
unsigned long reg = 0;
if (has_tls_reg && !tls_emu)
__asm__("mrc p15, 0, %0, c13, c0, 2" : "=r" (reg));
return reg;
}
static inline void set_tpuser(unsigned long val)
{
/* Since TPIDRURW is fully context-switched (unlike TPIDRURO),
* we need not update thread_info.
*/
if (has_tls_reg && !tls_emu) {
asm("mcr p15, 0, %0, c13, c0, 2"
: : "r" (val));
}
}
static inline void flush_tls(void)
{
set_tls(0);
set_tpuser(0);
}
#endif
#endif /* __ASMARM_TLS_H */